We typically associate bacteria with infectious diseases. In reality, only a few known bacteria actually cause disease. Most bacteria are actually very beneficial.
The digestive tract contains several hundreds of billions of bacteria. To put this into perspective, bacteria make up to 1 kilogram (that is 2.2 pounds) of your body weight. These bacteria form what is called the intestinal flora. This flora plays an essential role during digestion. In particular, it breaks down certain nutrients that the body cannot digest. Dietary fibre for example.
The density of bacteria increases gradually from the stomach to the large intestine. There are up to 1000 billion bacteria per gram of faecal matter, which means that there are about 10 times more bacteria in the digestive tract then there are cells in the body!
This intestinal flora consists of a unique ecosystem made up of several hundreds of species. Besides playing an important role in digestion, intestinal flora also helps maintain health and prevent the development of certain diseases.